Support visibility control and default to `internal`. (#3380)

* Support visibility control and default to `internal`.

* Fix wip.

* Fixes.

* Fix.

* Fix test.

* Add legacy language detection and compatibility for existing code.

* Add doc.

---------

Co-authored-by: Yong He <yhe@nvidia.com>

66 files changed, 356 insertions, 217 deletions

diff --git a/tests/autodiff/bsdf/bsdf-auto-rev.slang b/tests/autodiff/bsdf/bsdf-auto-rev.slang
index cd31f2097..1bb1989bf 100644
--- a/tests/autodiff/bsdf/bsdf-auto-rev.slang
+++ b/tests/autodiff/bsdf/bsdf-auto-rev.slang
@@ -1,4 +1,5 @@
 //TEST_IGNORE_FILE:
+implementing "bsdf-sample";
 
 struct ShadingData
 {
@@ -103,4 +104,4 @@ float bsdfGGXPDF(in float3 hLocal, in Auto_Bwd_BSDFParameters params)
     float d = ((cosTheta * a2 - cosTheta) * cosTheta + 1);
 
     return (a2 / (d * d * 3.1415926)) * cosTheta;
-}
\ No newline at end of file
+}
diff --git a/tests/autodiff/bsdf/bsdf-sample.slang b/tests/autodiff/bsdf/bsdf-sample.slang
index 8a9508791..9dfecf97e 100644
--- a/tests/autodiff/bsdf/bsdf-sample.slang
+++ b/tests/autodiff/bsdf/bsdf-sample.slang
@@ -2,9 +2,10 @@
 //TEST(compute):COMPARE_COMPUTE_EX:-slang -compute -shaderobj -output-using-type
 
 //TEST_INPUT:ubuffer(data=[0 0 0 0 0 0 0 0 0 0], stride=4):out,name=outputBuffer
-RWStructuredBuffer<float> outputBuffer;
+module "bsdf-sample";
+__include bsdf_auto_rev;
 
-__exported import bsdf_auto_rev;
+RWStructuredBuffer<float> outputBuffer;
 
 [numthreads(1, 1, 1)]
 void computeMain(uint3 dispatchThreadID: SV_DispatchThreadID)
diff --git a/tests/autodiff/cuda-kernel-export.slang b/tests/autodiff/cuda-kernel-export.slang
index 928133c94..39815ede8 100644
--- a/tests/autodiff/cuda-kernel-export.slang
+++ b/tests/autodiff/cuda-kernel-export.slang
@@ -35,7 +35,7 @@ void myKernel(TensorView<float> inValues, TensorView<float> outValues)
 // TORCH:      {{^SLANG_PRELUDE_EXPORT$}}
 // TORCH-NEXT: std::tuple<std::tuple<float, float>, std::tuple<std::tuple<std::tuple<torch::Tensor, torch::Tensor>>, std::tuple<std::tuple<torch::Tensor, torch::Tensor>>>> runCompute(std::tuple<torch::Tensor, float> input_[[#]])
 [TorchEntryPoint]
-public __extern_cpp MyType runCompute(MyInput input)
+export __extern_cpp MyType runCompute(MyInput input)
 {
     MyType rs;
     var outValues = TorchTensor<float>.alloc(1);
diff --git a/tests/autodiff/material/DiffuseMaterial.slang b/tests/autodiff/material/DiffuseMaterial.slang
index e762e17c8..3dd2927f5 100644
--- a/tests/autodiff/material/DiffuseMaterial.slang
+++ b/tests/autodiff/material/DiffuseMaterial.slang
@@ -3,13 +3,13 @@
 __exported import IMaterial;
 __exported import DiffuseMaterialInstance;
 
-struct DiffuseMaterial : IMaterial
+public struct DiffuseMaterial : IMaterial
 {
-    float3 baseColor;
+    public float3 baseColor;
 
-    typedef DiffuseMaterialInstance MaterialInstance;
+    public typedef DiffuseMaterialInstance MaterialInstance;
 
-    DiffuseMaterialInstance setupMaterialInstance()
+    public DiffuseMaterialInstance setupMaterialInstance()
     {
         DiffuseMaterialInstance mi = { {baseColor} };
         return mi;
diff --git a/tests/autodiff/material/DiffuseMaterialInstance.slang b/tests/autodiff/material/DiffuseMaterialInstance.slang
index ca6bfc69a..c6f0e315b 100644
--- a/tests/autodiff/material/DiffuseMaterialInstance.slang
+++ b/tests/autodiff/material/DiffuseMaterialInstance.slang
@@ -3,23 +3,23 @@
 __exported import IMaterialInstance;
 __exported import IBSDF;
 
-struct DiffuseBSDF : IBSDF
+public struct DiffuseBSDF : IBSDF
 {
-    float3 albedo;
+    public float3 albedo;
 
     [TreatAsDifferentiable]
-    float3 eval(const float3 wiLocal, const float3 woLocal)
+    public float3 eval(const float3 wiLocal, const float3 woLocal)
     {
         return albedo;
     }
 };
 
-struct DiffuseMaterialInstance : IMaterialInstance
+public struct DiffuseMaterialInstance : IMaterialInstance
 {
-    DiffuseBSDF bsdf;
+    public DiffuseBSDF bsdf;
 
     [TreatAsDifferentiable]
-    float3 eval(const float3 wi, const float3 wo)
+    public float3 eval(const float3 wi, const float3 wo)
     {
         return bsdf.eval(wi, wo);
     }
diff --git a/tests/autodiff/material/GlossyMaterial.slang b/tests/autodiff/material/GlossyMaterial.slang
index 59cee5afe..9848c82ed 100644
--- a/tests/autodiff/material/GlossyMaterial.slang
+++ b/tests/autodiff/material/GlossyMaterial.slang
@@ -3,13 +3,13 @@
 __exported import IMaterial;
 __exported import GlossyMaterialInstance;
 
-struct GlossyMaterial : IMaterial
+public struct GlossyMaterial : IMaterial
 {
-    float3 baseColor;
+    public float3 baseColor;
 
-    typedef GlossyMaterialInstance MaterialInstance;
+    public typedef GlossyMaterialInstance MaterialInstance;
 
-    GlossyMaterialInstance setupMaterialInstance()
+    public GlossyMaterialInstance setupMaterialInstance()
     {
         GlossyMaterialInstance mi = { { baseColor } };
         return mi;
diff --git a/tests/autodiff/material/GlossyMaterialInstance.slang b/tests/autodiff/material/GlossyMaterialInstance.slang
index fbbcc1a26..fb1ce55c0 100644
--- a/tests/autodiff/material/GlossyMaterialInstance.slang
+++ b/tests/autodiff/material/GlossyMaterialInstance.slang
@@ -3,44 +3,44 @@
 __exported import IMaterialInstance;
 __exported import IBSDF;
 
-struct GlossyBSDF : IBSDF
+public struct GlossyBSDF : IBSDF
 {
-    float3 albedo;
+    public float3 albedo;
 
-    float3 getAlbedo()
+    public float3 getAlbedo()
     {
         return albedo;
     }
 
     [ForwardDerivativeOf(getAlbedo)]
     [TreatAsDifferentiable]
-    DifferentialPair<float3> __fwd_d_getAlbedo()
+    public DifferentialPair<float3> __fwd_d_getAlbedo()
     {
         return diffPair(albedo, float3(1.f));
     }
 
     [BackwardDerivativeOf(getAlbedo)]
     [TreatAsDifferentiable]
-    void __bwd_d_getAlbedo(float3 dOut)
+    public void __bwd_d_getAlbedo(float3 dOut)
     {
         [unroll]
         for (int j = 0; j < 3; j++) outputBuffer[j + 3] += dOut[j];
     }
 
     [BackwardDifferentiable]
-    float3 eval(const float3 wiLocal, const float3 woLocal)
+    public float3 eval(const float3 wiLocal, const float3 woLocal)
     {
         float3 a = getAlbedo();
         return a * a;
     }
 };
 
-struct GlossyMaterialInstance : IMaterialInstance
+public struct GlossyMaterialInstance : IMaterialInstance
 {
-    GlossyBSDF bsdf;
+    public GlossyBSDF bsdf;
 
     [BackwardDifferentiable]
-    float3 eval(const float3 wi, const float3 wo)
+    public float3 eval(const float3 wi, const float3 wo)
     {
         return bsdf.eval(wi, wo);
     }
diff --git a/tests/autodiff/material/IBSDF.slang b/tests/autodiff/material/IBSDF.slang
index 9bdeb9197..933392b80 100644
--- a/tests/autodiff/material/IBSDF.slang
+++ b/tests/autodiff/material/IBSDF.slang
@@ -1,9 +1,9 @@
 //TEST_IGNORE_FILE:
 
 //TEST_INPUT:ubuffer(data=[0 0 0 0 0 0], stride=4):out,name=outputBuffer
-RWStructuredBuffer<float> outputBuffer;
+public RWStructuredBuffer<float> outputBuffer;
 
-interface IBSDF
+public interface IBSDF
 {
     [BackwardDifferentiable]
     float3 eval(const float3 wi, const float3 wo);
diff --git a/tests/autodiff/material/IMaterial.slang b/tests/autodiff/material/IMaterial.slang
index 4bdaac2bc..73390ba0e 100644
--- a/tests/autodiff/material/IMaterial.slang
+++ b/tests/autodiff/material/IMaterial.slang
@@ -2,9 +2,9 @@
 
 __exported import IMaterialInstance;
 
-interface IMaterial
+public interface IMaterial
 {
-    associatedtype MaterialInstance : IMaterialInstance;
+    public associatedtype MaterialInstance : IMaterialInstance;
 
-    MaterialInstance setupMaterialInstance();
+    public MaterialInstance setupMaterialInstance();
 }
diff --git a/tests/autodiff/material/IMaterialInstance.slang b/tests/autodiff/material/IMaterialInstance.slang
index fb13f8982..4425c2c65 100644
--- a/tests/autodiff/material/IMaterialInstance.slang
+++ b/tests/autodiff/material/IMaterialInstance.slang
@@ -1,7 +1,7 @@
 //TEST_IGNORE_FILE:
 
-interface IMaterialInstance
+public interface IMaterialInstance
 {
     [BackwardDifferentiable]
-    float3 eval(const float3 wi, const float3 wo);
+    public float3 eval(const float3 wi, const float3 wo);
 }
diff --git a/tests/autodiff/material/MaterialSystem.slang b/tests/autodiff/material/MaterialSystem.slang
index 5e733fad9..9fcee1386 100644
--- a/tests/autodiff/material/MaterialSystem.slang
+++ b/tests/autodiff/material/MaterialSystem.slang
@@ -2,7 +2,7 @@
 
 __exported import IMaterial;
 
-IMaterial createMaterialClassConformance(int type, float3 value)
+public IMaterial createMaterialClassConformance(int type, float3 value)
 {
     return createDynamicObject<IMaterial, float3>(type, value);
 }
diff --git a/tests/autodiff/material2/DiffuseMaterial.slang b/tests/autodiff/material2/DiffuseMaterial.slang
index 721445249..d4ae579ff 100644
--- a/tests/autodiff/material2/DiffuseMaterial.slang
+++ b/tests/autodiff/material2/DiffuseMaterial.slang
@@ -3,20 +3,20 @@
 __exported import IMaterial;
 __exported import DiffuseMaterialInstance;
 
-struct DiffuseMaterial : IMaterial
+public struct DiffuseMaterial : IMaterial
 {
-    float3 baseColor;
+    public float3 baseColor;
 
-    typedef DiffuseMaterialInstance MaterialInstance;
+    public typedef DiffuseMaterialInstance MaterialInstance;
 
     [TreatAsDifferentiable]
-    float3 getAlbedo(float3 albedo)
+    public float3 getAlbedo(float3 albedo)
     {
         return albedo;
     }
 
     [BackwardDifferentiable]
-    DiffuseMaterialInstance setupMaterialInstance(out MaterialInstanceData miData)
+    public DiffuseMaterialInstance setupMaterialInstance(out MaterialInstanceData miData)
     {
         float3 albedo = getAlbedo(baseColor);
         DiffuseMaterialInstance mi = { baseColor };
diff --git a/tests/autodiff/material2/DiffuseMaterialInstance.slang b/tests/autodiff/material2/DiffuseMaterialInstance.slang
index e33e3f568..7f8421d9f 100644
--- a/tests/autodiff/material2/DiffuseMaterialInstance.slang
+++ b/tests/autodiff/material2/DiffuseMaterialInstance.slang
@@ -3,12 +3,12 @@
 __exported import IMaterialInstance;
 __exported import IBSDF;
 
-struct DiffuseMaterialInstance : IMaterialInstance
+public struct DiffuseMaterialInstance : IMaterialInstance
 {
-    float3 albedo;
+    public float3 albedo;
 
     [BackwardDifferentiable]
-    float3 eval(const MaterialInstanceData miData, const float3 wi, const float3 wo)
+    public float3 eval(const MaterialInstanceData miData, const float3 wi, const float3 wo)
     {
         float3 albedo;
         for (uint i = 0; i < 3; i++) albedo[i] = miData.data[i];
diff --git a/tests/autodiff/material2/GlossyMaterial.slang b/tests/autodiff/material2/GlossyMaterial.slang
index 34ade54cb..e937443d4 100644
--- a/tests/autodiff/material2/GlossyMaterial.slang
+++ b/tests/autodiff/material2/GlossyMaterial.slang
@@ -3,34 +3,34 @@
 __exported import IMaterial;
 __exported import GlossyMaterialInstance;
 
-struct GlossyMaterial : IMaterial
+public struct GlossyMaterial : IMaterial
 {
-    float3 baseColor;
+    public float3 baseColor;
 
-    typedef GlossyMaterialInstance MaterialInstance;
+    public typedef GlossyMaterialInstance MaterialInstance;
 
-    float3 getAlbedo(float3 albedo)
+    public float3 getAlbedo(float3 albedo)
     {
         return albedo;
     }
 
     [ForwardDerivativeOf(getAlbedo)]
     [TreatAsDifferentiable]
-    DifferentialPair<float3> __fwd_d_getAlbedo(DifferentialPair<float3> dpAlbedo)
+    public DifferentialPair<float3> __fwd_d_getAlbedo(DifferentialPair<float3> dpAlbedo)
     {
         return diffPair(dpAlbedo.p, float3(1.f));
     }
 
     [BackwardDerivativeOf(getAlbedo)]
     [TreatAsDifferentiable]
-    void __bwd_d_getAlbedo(inout DifferentialPair<float3> dpAlbedo, float3 dOut)
+    public void __bwd_d_getAlbedo(inout DifferentialPair<float3> dpAlbedo, float3 dOut)
     {
         [unroll]
         for (int j = 0; j < 3; j++) outputBuffer[j + 3] += dOut[j];
     }
 
     [BackwardDifferentiable]
-    GlossyMaterialInstance setupMaterialInstance(out MaterialInstanceData miData)
+    public GlossyMaterialInstance setupMaterialInstance(out MaterialInstanceData miData)
     {
         float3 albedo = getAlbedo(baseColor);
         GlossyMaterialInstance mi = { baseColor };
diff --git a/tests/autodiff/material2/GlossyMaterialInstance.slang b/tests/autodiff/material2/GlossyMaterialInstance.slang
index 3cef458ff..64973a5ea 100644
--- a/tests/autodiff/material2/GlossyMaterialInstance.slang
+++ b/tests/autodiff/material2/GlossyMaterialInstance.slang
@@ -3,12 +3,12 @@
 __exported import IMaterialInstance;
 __exported import IBSDF;
 
-struct GlossyMaterialInstance : IMaterialInstance
+public struct GlossyMaterialInstance : IMaterialInstance
 {
-    float3 albedo;
+    public float3 albedo;
 
     [BackwardDifferentiable]
-    float3 eval(const MaterialInstanceData miData, const float3 wi, const float3 wo)
+    public float3 eval(const MaterialInstanceData miData, const float3 wi, const float3 wo)
     {
         float3 albedo = float3(0.0f, 0.0f, 0.0f);
         for (uint i = 0; i < 3; i++) albedo[i] = miData.data[i];
diff --git a/tests/autodiff/material2/IBSDF.slang b/tests/autodiff/material2/IBSDF.slang
index 57cff2883..49bfde6e7 100644
--- a/tests/autodiff/material2/IBSDF.slang
+++ b/tests/autodiff/material2/IBSDF.slang
@@ -1,10 +1,10 @@
 //TEST_IGNORE_FILE:
 
-//TEST_INPUT:ubuffer(data=[0 0 0 0 0 0 0 0 0], stride=4):out,name=outputBuffer
-RWStructuredBuffer<float> outputBuffer;
+// TEST_INPUT:ubuffer(data=[0 0 0 0 0 0 0 0 0], stride=4):out,name=outputBuffer
+public RWStructuredBuffer<float> outputBuffer;
 
-interface IBSDF
+public interface IBSDF
 {
     [BackwardDifferentiable]
-    float3 eval(const float3 wi, const float3 wo);
+    public float3 eval(const float3 wi, const float3 wo);
 }
diff --git a/tests/autodiff/material2/IMaterial.slang b/tests/autodiff/material2/IMaterial.slang
index 66780c9ff..cefb69393 100644
--- a/tests/autodiff/material2/IMaterial.slang
+++ b/tests/autodiff/material2/IMaterial.slang
@@ -2,10 +2,10 @@
 
 __exported import IMaterialInstance;
 
-interface IMaterial
+public interface IMaterial
 {
-    associatedtype MaterialInstance : IMaterialInstance;
+    public associatedtype MaterialInstance : IMaterialInstance;
 
     [BackwardDifferentiable]
-    MaterialInstance setupMaterialInstance(out MaterialInstanceData miData);
+    public MaterialInstance setupMaterialInstance(out MaterialInstanceData miData);
 }
diff --git a/tests/autodiff/material2/IMaterialInstance.slang b/tests/autodiff/material2/IMaterialInstance.slang
index ddf5ca0f6..6b6b617b5 100644
--- a/tests/autodiff/material2/IMaterialInstance.slang
+++ b/tests/autodiff/material2/IMaterialInstance.slang
@@ -1,8 +1,8 @@
 //TEST_IGNORE_FILE:
 
-struct MaterialInstanceData : IDifferentiable
+public struct MaterialInstanceData : IDifferentiable
 {
-    float data[5];
+    public float data[5];
 }
 
 /*
@@ -13,8 +13,8 @@ struct MaterialInstanceSetupResult : IDifferentiable
 }
 */
 
-interface IMaterialInstance
+public interface IMaterialInstance
 {
     [BackwardDifferentiable]
-    float3 eval(const MaterialInstanceData miData, const float3 wi, const float3 wo);
+    public float3 eval(const MaterialInstanceData miData, const float3 wi, const float3 wo);
 }
diff --git a/tests/autodiff/material2/MaterialSystem.slang b/tests/autodiff/material2/MaterialSystem.slang
index 5e733fad9..9fcee1386 100644
--- a/tests/autodiff/material2/MaterialSystem.slang
+++ b/tests/autodiff/material2/MaterialSystem.slang
@@ -2,7 +2,7 @@
 
 __exported import IMaterial;
 
-IMaterial createMaterialClassConformance(int type, float3 value)
+public IMaterial createMaterialClassConformance(int type, float3 value)
 {
     return createDynamicObject<IMaterial, float3>(type, value);
 }
diff --git a/tests/autodiff/material2/MxLayeredMaterial.slang b/tests/autodiff/material2/MxLayeredMaterial.slang
index 5e2717b60..8c5cd6d3c 100644
--- a/tests/autodiff/material2/MxLayeredMaterial.slang
+++ b/tests/autodiff/material2/MxLayeredMaterial.slang
@@ -5,54 +5,54 @@ __exported import IMaterialInstance;
 import MxLayeredMaterialInstance;
 import MxWeights;
 
-struct LayeredData_mixedLobes : IMxLayeredMaterialData
+public struct LayeredData_mixedLobes : IMxLayeredMaterialData
 {
-    static const int bsdfCount = 3;
-    static const int layerCount = 1;
+    public static const int bsdfCount = 3;
+    public static const int layerCount = 1;
 
-    int getBsdfCount() { return bsdfCount; }
-    int getLayerCount() { return layerCount; }
+    public int getBsdfCount() { return bsdfCount; }
+    public int getLayerCount() { return layerCount; }
 }
 #define TMxLayeredMaterialData LayeredData_mixedLobes
 
-struct Layered_mixedLobes_WeightsCalculator : IMxLayeredWeightCalculator
+public struct Layered_mixedLobes_WeightsCalculator : IMxLayeredWeightCalculator
 {
-    void calculateWeights<let TBsdfCount : int, let TLayerCount : int, TLayeredMaterialData : IMxLayeredMaterialData>(
+    public void calculateWeights<let TBsdfCount : int, let TLayerCount : int, TLayeredMaterialData : IMxLayeredMaterialData>(
         const TLayeredMaterialData data, out MxWeights<TBsdfCount> weights)
     {
         for (uint i = 0; i < TBsdfCount; i++) weights.weights[i] = float3(0.f);
     }
 }
 
-struct MxLayeredMaterial : IMaterial
+public struct MxLayeredMaterial : IMaterial
 {
-    float3 baseColor;
+    public float3 baseColor;
 
-    typealias UsedMaterialInstance = MxLayeredMaterialInstance<3, 1, TMxLayeredMaterialData, Layered_mixedLobes_WeightsCalculator>;
-    typedef UsedMaterialInstance MaterialInstance;    
+    public typealias UsedMaterialInstance = MxLayeredMaterialInstance<3, 1, TMxLayeredMaterialData, Layered_mixedLobes_WeightsCalculator>;
+    public typedef UsedMaterialInstance MaterialInstance;
 
-    float3 getAlbedo(float3 albedo)
+    public float3 getAlbedo(float3 albedo)
     {
         return albedo;
     }
 
     [ForwardDerivativeOf(getAlbedo)]
     [TreatAsDifferentiable]
-    DifferentialPair<float3> __fwd_d_getAlbedo(DifferentialPair<float3> dpAlbedo)
+    public DifferentialPair<float3> __fwd_d_getAlbedo(DifferentialPair<float3> dpAlbedo)
     {
         return diffPair(dpAlbedo.p, float3(1.f));
     }
 
     [BackwardDerivativeOf(getAlbedo)]
     [TreatAsDifferentiable]
-    void __bwd_d_getAlbedo(inout DifferentialPair<float3> dpAlbedo, float3 dOut)
+    public void __bwd_d_getAlbedo(inout DifferentialPair<float3> dpAlbedo, float3 dOut)
     {
         [unroll]
         for (int j = 0; j < 3; j++) outputBuffer[j + 6] += dOut[j];
     }
-    
+
     [Differentiable]
-    UsedMaterialInstance setupMaterialInstance(out MaterialInstanceData miData)
+    public UsedMaterialInstance setupMaterialInstance(out MaterialInstanceData miData)
     {
         float3 albedo = getAlbedo(baseColor);
         UsedMaterialInstance mi;
diff --git a/tests/autodiff/material2/MxLayeredMaterialInstance.slang b/tests/autodiff/material2/MxLayeredMaterialInstance.slang
index 53a319d6f..ed2ef1cb0 100644
--- a/tests/autodiff/material2/MxLayeredMaterialInstance.slang
+++ b/tests/autodiff/material2/MxLayeredMaterialInstance.slang
@@ -5,17 +5,17 @@ __exported import IBSDF;
 
 import MxWeights;
 
-struct MxLayeredMaterialInstance<
+public struct MxLayeredMaterialInstance<
     let TBsdfCount : int,
     let TLayerCount : int,
     TLayeredMaterialData : IMxLayeredMaterialData,
     TWeightsCalc : IMxLayeredWeightCalculator> : IMaterialInstance
 {
-    TLayeredMaterialData data;
-    TWeightsCalc calculator;
-    typealias Weights = MxWeights<TBsdfCount>;
+    public TLayeredMaterialData data;
+    public TWeightsCalc calculator;
+    public typealias Weights = MxWeights<TBsdfCount>;
 
-    Weights calculateWeights()
+    public Weights calculateWeights()
     {
         Weights result;
         calculator.calculateWeights<TBsdfCount, TLayerCount, TLayeredMaterialData>(data, result);
@@ -23,7 +23,7 @@ struct MxLayeredMaterialInstance<
     }
 
     [Differentiable]
-    float3 eval(const MaterialInstanceData miData, const float3 wi, const float3 wo)
+    public float3 eval(const MaterialInstanceData miData, const float3 wi, const float3 wo)
     {
         float3 albedo;
         for (uint i = 0; i < 3; i++) albedo[i] = miData.data[i];
diff --git a/tests/autodiff/material2/MxWeights.slang b/tests/autodiff/material2/MxWeights.slang
index 1d1a9f543..1e9c7d36c 100644
--- a/tests/autodiff/material2/MxWeights.slang
+++ b/tests/autodiff/material2/MxWeights.slang
@@ -1,18 +1,18 @@
 //TEST_IGNORE_FILE:
 
-struct MxWeights<let TBsdfCount : int>
+public struct MxWeights<let TBsdfCount : int>
 {
-    float3 weights[TBsdfCount];
+    public float3 weights[TBsdfCount];
 }
 
-interface IMxLayeredMaterialData
+public interface IMxLayeredMaterialData
 {
-    int getBsdfCount();
-    int getLayerCount();
+    public int getBsdfCount();
+    public int getLayerCount();
 }
 
-interface IMxLayeredWeightCalculator
+public interface IMxLayeredWeightCalculator
 {
-    void calculateWeights<let TBsdfCount : int, let TLayerCount: int, TLayeredMaterialData : IMxLayeredMaterialData>(
+    public void calculateWeights<let TBsdfCount : int, let TLayerCount: int, TLayeredMaterialData : IMxLayeredMaterialData>(
         const TLayeredMaterialData data, out MxWeights<TBsdfCount> weights);
 }
diff --git a/tests/bindings/multi-file-defines.h b/tests/bindings/multi-file-defines.h
index 52a5826b6..db0261158 100644
--- a/tests/bindings/multi-file-defines.h
+++ b/tests/bindings/multi-file-defines.h
@@ -5,12 +5,13 @@
 #define BEGIN_CBUFFER(NAME) cbuffer NAME
 #define END_CBUFFER(NAME, REG) /**/
 #define CBUFFER_REF(NAME, FIELD) FIELD
+#define PUBLIC public
 #else
 #define R(X) X
 #define BEGIN_CBUFFER(NAME) struct SLANG_ParameterGroup_##NAME
 #define END_CBUFFER(NAME, REG) ; cbuffer NAME : REG { SLANG_ParameterGroup_##NAME NAME; }
 #define CBUFFER_REF(NAME, FIELD) NAME.FIELD
-
+#define PUBLIC 
 #define sharedC     sharedC_0
 #define sharedCA    sharedCA_0
 #define sharedCB    sharedCB_0
diff --git a/tests/bindings/multi-file-shared.slang b/tests/bindings/multi-file-shared.slang
index af91d5251..dcfa6251c 100644
--- a/tests/bindings/multi-file-shared.slang
+++ b/tests/bindings/multi-file-shared.slang
@@ -3,23 +3,23 @@
 
 #include "multi-file-defines.h"
 
-float4 use(float  val) { return val; };
-float4 use(float2 val) { return float4(val,0.0,0.0); };
-float4 use(float3 val) { return float4(val,0.0); };
-float4 use(float4 val) { return val; };
-float4 use(Texture2D t, SamplerState s) { return t.SampleLevel(s, 0.0, 0.0); }
+PUBLIC float4 use(float  val) { return val; };
+PUBLIC float4 use(float2 val) { return float4(val,0.0,0.0); };
+PUBLIC float4 use(float3 val) { return float4(val,0.0); };
+PUBLIC float4 use(float4 val) { return val; };
+PUBLIC float4 use(Texture2D t, SamplerState s) { return t.SampleLevel(s, 0.0, 0.0); }
 
-Texture2D sharedT R(: register(t2));
-SamplerState sharedS R(: register(s2));
+PUBLIC Texture2D sharedT R(: register(t2));
+PUBLIC SamplerState sharedS R(: register(s2));
 
-BEGIN_CBUFFER(sharedC)
+PUBLIC BEGIN_CBUFFER(sharedC)
 {
-	float3 sharedCA;
-	float  sharedCB;
-	float3 sharedCC;
-	float2 sharedCD;
+    PUBLIC float3 sharedCA;
+    PUBLIC float sharedCB;
+    PUBLIC float3 sharedCC;
+    PUBLIC float2 sharedCD;
 }
 END_CBUFFER(sharedC, register(b2))
 
-Texture2D sharedTV R(: register(t3));
-Texture2D sharedTF R(: register(t4));
+PUBLIC Texture2D sharedTV R(: register(t3));
+PUBLIC Texture2D sharedTF R(: register(t4));
diff --git a/tests/bugs/gl-33-ext.slang b/tests/bugs/gl-33-ext.slang
index ae70cfaf0..fccde99a3 100644
--- a/tests/bugs/gl-33-ext.slang
+++ b/tests/bugs/gl-33-ext.slang
@@ -1,8 +1,8 @@
 // gl-33-ext.slang
 //TEST_IGNORE_FILE:
 
-struct A
+public struct A
 {
-    int state;
-    [mutating] int next() { return state; }
+    public int state;
+    [mutating] public int next() { return state; }
 };
diff --git a/tests/bugs/interface-lvalue.slang b/tests/bugs/interface-lvalue.slang
index 87cfa54ed..e80a130d1 100644
--- a/tests/bugs/interface-lvalue.slang
+++ b/tests/bugs/interface-lvalue.slang
@@ -23,7 +23,7 @@ void createFoo(out IFoo val)
     val = resuult;
 }
 
-public __extern_cpp int main()
+export __extern_cpp int main()
 {
     IFoo v;
     createFoo(v);
diff --git a/tests/bugs/split-nested-types.slang b/tests/bugs/split-nested-types.slang
index 3bd4e239f..b9bfb9e62 100644
--- a/tests/bugs/split-nested-types.slang
+++ b/tests/bugs/split-nested-types.slang
@@ -1,14 +1,14 @@
 //TEST_IGNORE_FILE:
 
-struct A { int x; };
+public struct A { public int x; };
 
-struct B { float y; };
+public struct B { public float y; };
 
-struct CC { Texture2D t; SamplerState s; };
+public struct CC { public Texture2D t; public SamplerState s; };
 
-struct M
+public struct M
 {
-	A a;
-	B b;
-	CC c;
+    public A a;
+    public B b;
+    public CC c;
 };
diff --git a/tests/compute/array-existential-parameter.slang b/tests/compute/array-existential-parameter.slang
index 813c5a40b..b7473e447 100644
--- a/tests/compute/array-existential-parameter.slang
+++ b/tests/compute/array-existential-parameter.slang
@@ -38,7 +38,7 @@ void computeMain(uint3       dispatchThreadID : SV_DispatchThreadID)
 //TEST_INPUT: globalExistentialType __Dynamic
 
 // Type must be marked `public` to ensure it is visible in the generated DLL.
-public struct MyImpl : IInterface
+export struct MyImpl : IInterface
 {
     int val;
     int run(int input)
diff --git a/tests/compute/dynamic-dispatch-11.slang b/tests/compute/dynamic-dispatch-11.slang
index d6f64aa99..59e7ce581 100644
--- a/tests/compute/dynamic-dispatch-11.slang
+++ b/tests/compute/dynamic-dispatch-11.slang
@@ -34,7 +34,7 @@ void computeMain(uint3       dispatchThreadID : SV_DispatchThreadID)
 
 // No type input for dynamic dispatch //TEST_INPUT: globalExistentialType MyImpl
 // Type must be marked `public` to ensure it is visible in the generated DLL.
-public struct MyImpl : IInterface
+export struct MyImpl : IInterface
 {
     int val;
     int run(int input)
diff --git a/tests/compute/dynamic-dispatch-12.slang b/tests/compute/dynamic-dispatch-12.slang
index 906a5da0e..28f9c4c14 100644
--- a/tests/compute/dynamic-dispatch-12.slang
+++ b/tests/compute/dynamic-dispatch-12.slang
@@ -37,14 +37,14 @@ void computeMain(uint3       dispatchThreadID : SV_DispatchThreadID)
 }
 
 // Specialize gCb1, but not gCb2
-//TEST_INPUT: globalExistentialType MyImpl
-//TEST_INPUT: globalExistentialType __Dynamic
+// TEST_INPUT: globalExistentialType MyImpl
+// TEST_INPUT: globalExistentialType __Dynamic
 // Type must be marked `public` to ensure it is visible in the generated DLL.
-public struct MyImpl : IInterface
+export struct MyImpl : IInterface
 {
     int val;
     int run(int input)
     {
         return input + val;
     }
-};
\ No newline at end of file
+};
diff --git a/tests/compute/dynamic-dispatch-13.slang b/tests/compute/dynamic-dispatch-13.slang
index f9ad9683b..20d78e0ad 100644
--- a/tests/compute/dynamic-dispatch-13.slang
+++ b/tests/compute/dynamic-dispatch-13.slang
@@ -35,7 +35,7 @@ void computeMain(int3       dispatchThreadID : SV_DispatchThreadID)
 }
 
 // Type must be marked `public` to ensure it is visible in the generated DLL.
-public struct MyImpl : IInterface
+export struct MyImpl : IInterface
 {
     int val;
     int run(int input)
@@ -43,7 +43,7 @@ public struct MyImpl : IInterface
         return input + val;
     }
 };
-public struct MyImpl2 : IInterface
+export struct MyImpl2 : IInterface
 {
     int val;
     int run(int input)
diff --git a/tests/compute/dynamic-dispatch-14.slang b/tests/compute/dynamic-dispatch-14.slang
index e605132c6..0dc99b432 100644
--- a/tests/compute/dynamic-dispatch-14.slang
+++ b/tests/compute/dynamic-dispatch-14.slang
@@ -46,10 +46,10 @@ void computeMain(int3       dispatchThreadID : SV_DispatchThreadID)
 }
 
 // Type must be marked `public` to ensure it is visible in the generated DLL.
-public struct MyImpl : IInterface
+export struct MyImpl : IInterface
 {
     int val;
-    public struct TAssoc : IAssoc
+    export struct TAssoc : IAssoc
     {
         int val;
         int eval() { return val; }
@@ -62,10 +62,10 @@ public struct MyImpl : IInterface
     }
 };
 
-public struct MyImpl2 : IInterface
+export struct MyImpl2 : IInterface
 {
     int val;
-    public struct TAssoc : IAssoc
+    export struct TAssoc : IAssoc
     {
         int val;
         int eval() { return val; }
@@ -76,4 +76,4 @@ public struct MyImpl2 : IInterface
         rs.val = input - val;
         return rs;
     }
-};
\ No newline at end of file
+};
diff --git a/tests/compute/dynamic-dispatch-15.slang b/tests/compute/dynamic-dispatch-15.slang
index 5e2be1a4c..2ab169281 100644
--- a/tests/compute/dynamic-dispatch-15.slang
+++ b/tests/compute/dynamic-dispatch-15.slang
@@ -46,7 +46,7 @@ void computeMain(uint3       dispatchThreadID : SV_DispatchThreadID)
 }
 
 // Type must be marked `public` to ensure it is visible in the generated DLL.
-public struct FloatVal : IInterface
+export struct FloatVal : IInterface
 {
     float val;
     float run()
@@ -56,7 +56,7 @@ public struct FloatVal : IInterface
 };
 interface ISomething{void g();}
 struct Float4Struct : ISomething { float4 val; void g() {} }
-public struct Float4Val : IInterface
+export struct Float4Val : IInterface
 {
     Float4Struct val;
     float run()
@@ -64,7 +64,7 @@ public struct Float4Val : IInterface
         return val.val.x;
     }
 };
-public struct IntVal : IInterface
+export struct IntVal : IInterface
 {
     int val;
     float run()
@@ -72,11 +72,11 @@ public struct IntVal : IInterface
         return val;
     }
 };
-public struct Int4Val : IInterface
+export struct Int4Val : IInterface
 {
     int4 val;
     float run()
     {
         return val.x;
     }
-};
\ No newline at end of file
+};
diff --git a/tests/compute/dynamic-dispatch-bindless-texture.slang b/tests/compute/dynamic-dispatch-bindless-texture.slang
index 04c1f1766..34ef67d1e 100644
--- a/tests/compute/dynamic-dispatch-bindless-texture.slang
+++ b/tests/compute/dynamic-dispatch-bindless-texture.slang
@@ -28,7 +28,7 @@ void computeMain(int3       dispatchThreadID : SV_DispatchThreadID)
 //TEST_INPUT: globalExistentialType __Dynamic
 
 // Type must be marked `public` to ensure it is visible in the generated DLL.
-public struct MyImpl : IInterface
+export struct MyImpl : IInterface
 {
     Texture2D tex;
     SamplerState sampler;
diff --git a/tests/compute/interface-assoc-type-param.slang b/tests/compute/interface-assoc-type-param.slang
index 805f673a2..a234d457f 100644
--- a/tests/compute/interface-assoc-type-param.slang
+++ b/tests/compute/interface-assoc-type-param.slang
@@ -16,7 +16,7 @@ interface IEval
     uint eval();
 }
 
-public struct Impl : IInterface
+export struct Impl : IInterface
 {
     uint val;
     struct TEval : IEval
@@ -55,4 +55,4 @@ void computeMain(uint3 dispatchThreadID : SV_DispatchThreadID,
 {
 	uint tid = dispatchThreadID.x;
 	compute(tid, params);
-}
\ No newline at end of file
+}
diff --git a/tests/compute/interface-func-param-in-struct.slang b/tests/compute/interface-func-param-in-struct.slang
index c47b25d70..01e4aa111 100644
--- a/tests/compute/interface-func-param-in-struct.slang
+++ b/tests/compute/interface-func-param-in-struct.slang
@@ -9,7 +9,7 @@ interface IInterface
     uint eval();
 }
 
-public struct Impl : IInterface
+export struct Impl : IInterface
 {
     uint val;
     uint eval()
@@ -38,4 +38,4 @@ void computeMain(uint3 dispatchThreadID : SV_DispatchThreadID,
 {
 	uint tid = dispatchThreadID.x;
 	compute(tid, params);
-}
\ No newline at end of file
+}
diff --git a/tests/compute/interface-param-partial-specialize.slang b/tests/compute/interface-param-partial-specialize.slang
index 9be22c6c4..1d09c9f55 100644
--- a/tests/compute/interface-param-partial-specialize.slang
+++ b/tests/compute/interface-param-partial-specialize.slang
@@ -12,7 +12,7 @@ interface IInterface
     uint eval();
 }
 
-public struct Impl : IInterface
+export struct Impl : IInterface
 {
     uint val;
     uint eval()
@@ -48,4 +48,4 @@ void computeMain(uint3 dispatchThreadID : SV_DispatchThreadID,
 {
 	uint tid = dispatchThreadID.x;
 	compute(tid, params);
-}
\ No newline at end of file
+}
diff --git a/tests/cpu-program/class-com.slang b/tests/cpu-program/class-com.slang
index e2812f586..2dd84d696 100644
--- a/tests/cpu-program/class-com.slang
+++ b/tests/cpu-program/class-com.slang
@@ -20,7 +20,7 @@ class MyClass : IFoo
 };
 
 [DllExport]
-IFoo createFoo()
+export IFoo createFoo()
 {
     IFoo result = new MyClass();
     return result;
@@ -30,8 +30,8 @@ IFoo createFoo()
 [DllImport("", "createFoo")]
 IFoo createFooImported();
 
-public __extern_cpp int main()
+export __extern_cpp int main()
 {
     var obj = createFooImported();
     return obj.method();
-}
\ No newline at end of file
+}
diff --git a/tests/cpu-program/class.slang b/tests/cpu-program/class.slang
index 1a510118a..8935b157a 100644
--- a/tests/cpu-program/class.slang
+++ b/tests/cpu-program/class.slang
@@ -13,8 +13,8 @@ class MyClass
     }
 }
 
-public __extern_cpp int main()
+export __extern_cpp int main()
 {
     MyClass obj = new MyClass();
     return obj.method();
-}
\ No newline at end of file
+}
diff --git a/tests/cpu-program/cpu-hello-world.slang b/tests/cpu-program/cpu-hello-world.slang
index f1285f889..a44761e8f 100644
--- a/tests/cpu-program/cpu-hello-world.slang
+++ b/tests/cpu-program/cpu-hello-world.slang
@@ -1,6 +1,6 @@
 //TEST:EXECUTABLE:
 
-public __extern_cpp int main()
+export __extern_cpp int main()
 {
     printf("Hello World.\n");
     return 0;
diff --git a/tests/cpu-program/gfx-smoke.slang b/tests/cpu-program/gfx-smoke.slang
index d0acb83db..41c87ca19 100644
--- a/tests/cpu-program/gfx-smoke.slang
+++ b/tests/cpu-program/gfx-smoke.slang
@@ -2,7 +2,7 @@
 import gfx;
 import slang;
 
-public __extern_cpp int main()
+export __extern_cpp int main()
 {
     gfx.DeviceDesc deviceDesc = {};
     deviceDesc.deviceType = gfx.DeviceType.CPU;
@@ -98,4 +98,4 @@ public __extern_cpp int main()
         printf("%.1f\n", val);
     }
     return 0;
-}
\ No newline at end of file
+}
diff --git a/tests/cpu-program/pointer-basics.slang b/tests/cpu-program/pointer-basics.slang
index e38d866eb..db705d507 100644
--- a/tests/cpu-program/pointer-basics.slang
+++ b/tests/cpu-program/pointer-basics.slang
@@ -1,5 +1,5 @@
 //TEST:EXECUTABLE:
-public __extern_cpp int main()
+export __extern_cpp int main()
 {
     uint2 value;
     int *pValue = (int*)&value;
@@ -20,4 +20,4 @@ public __extern_cpp int main()
     else
         printf("Fail\n");
     return 0;
-}
\ No newline at end of file
+}
diff --git a/tests/cpu-program/pointer-deref.slang b/tests/cpu-program/pointer-deref.slang
index 79f1b2cd0..f5bad5b09 100644
--- a/tests/cpu-program/pointer-deref.slang
+++ b/tests/cpu-program/pointer-deref.slang
@@ -11,7 +11,7 @@ struct Record
     SubRecord sub;
 }
 
-public __extern_cpp int main()
+export __extern_cpp int main()
 {
     Record rec;
     Record *pRec = &rec;
@@ -27,4 +27,4 @@ public __extern_cpp int main()
         printf("fail\n");
     }
     return 0;
-}
\ No newline at end of file
+}
diff --git a/tests/current-bugs/resource-dynamic-dispatch.slang b/tests/current-bugs/resource-dynamic-dispatch.slang
index 0a987b1cf..f344448dd 100644
--- a/tests/current-bugs/resource-dynamic-dispatch.slang
+++ b/tests/current-bugs/resource-dynamic-dispatch.slang
@@ -26,13 +26,13 @@ interface IInterface
 };
 
 // Need public to make these conformances available
-public struct A : IInterface
+export struct A : IInterface
 {
     typedef SomeData Type;
     IGetTexture getType() { Type t = { gTexA }; return t; }
 };
 
-public struct B : IInterface
+export struct B : IInterface
 {
     typedef SomeData Type;
     IGetTexture getType() { Type t = { gTexB }; return t; }
@@ -64,4 +64,4 @@ void computeMain(uint3 dispatchThreadID : SV_DispatchThreadID)
     let tex = getTex.getTexture();
     
 	outputBuffer[tid] = tex.Load(int3(tid, tid, 0));
-}
\ No newline at end of file
+}
diff --git a/tests/diagnostics/extension-visibility-a.slang b/tests/diagnostics/extension-visibility-a.slang
index 97e4ef85c..162320d51 100644
--- a/tests/diagnostics/extension-visibility-a.slang
+++ b/tests/diagnostics/extension-visibility-a.slang
@@ -1,17 +1,17 @@
 // extension-visibility-a.slang
 
-interface IThing
+public interface IThing
 {
-	int getValue();
+	public int getValue();
 }
 
 // Note: not implementing the interface here!
-struct MyThing
+public struct MyThing
 {
-	int value;
+	public int value;
 }
 
-int helper<T : IThing>(T thing)
+public int helper<T : IThing>(T thing)
 {
 	return thing.getValue();
-}
\ No newline at end of file
+}
diff --git a/tests/diagnostics/extension-visibility-b.slang b/tests/diagnostics/extension-visibility-b.slang
index 7848f2a56..dbefe66e7 100644
--- a/tests/diagnostics/extension-visibility-b.slang
+++ b/tests/diagnostics/extension-visibility-b.slang
@@ -2,7 +2,7 @@
 
 import extension_visibility_a;
 
-extension MyThing : IThing
+public extension MyThing : IThing
 {
-	int getValue() { return value; }	
+	public int getValue() { return value; }	
 }
diff --git a/tests/diagnostics/extension-visibility-c.slang b/tests/diagnostics/extension-visibility-c.slang
index 2d7a5224d..71680b31e 100644
--- a/tests/diagnostics/extension-visibility-c.slang
+++ b/tests/diagnostics/extension-visibility-c.slang
@@ -3,7 +3,7 @@
 import extension_visibility_a;
 import extension_visibility_b;
 
-int works(MyThing thing)
+public int works(MyThing thing)
 {
 	return helper(thing);
 }
diff --git a/tests/diagnostics/extension-visibility.slang.expected b/tests/diagnostics/extension-visibility.slang.expected
index 732ff4189..eed86715d 100644
--- a/tests/diagnostics/extension-visibility.slang.expected
+++ b/tests/diagnostics/extension-visibility.slang.expected
@@ -3,9 +3,9 @@ standard error = {
 tests/diagnostics/extension-visibility.slang(17): error 39999: could not specialize generic for arguments of type (MyThing)
     return helper(thing);
                  ^
-tests/diagnostics/extension-visibility-a.slang(14): note 39999: see declaration of func helper<T>(T) -> int
-int helper<T : IThing>(T thing)
-    ^~~~~~
+tests/diagnostics/extension-visibility-a.slang(14): note 39999: see declaration of public func helper<T>(T) -> int
+public int helper<T : IThing>(T thing)
+           ^~~~~~
 }
 standard output = {
 }
diff --git a/tests/diagnostics/internal-visibility/that-module-impl.slang b/tests/diagnostics/internal-visibility/that-module-impl.slang
new file mode 100644
index 000000000..893510afe
--- /dev/null
+++ b/tests/diagnostics/internal-visibility/that-module-impl.slang
@@ -0,0 +1,17 @@
+implementing "that-module";
+
+
+public void publicFunc2() { }
+
+internal void internalFunc1() {}
+
+public struct PublicStruct
+{
+    int x;
+    public int y;
+}
+
+public namespace Namespace
+{
+    public static int publicVar2;
+}
diff --git a/tests/diagnostics/internal-visibility/that-module.slang b/tests/diagnostics/internal-visibility/that-module.slang
new file mode 100644
index 000000000..b072c7231
--- /dev/null
+++ b/tests/diagnostics/internal-visibility/that-module.slang
@@ -0,0 +1,25 @@
+module "that-module";
+
+__include "that-module-impl";
+
+void internalMethod();
+
+public void publicMethod();
+
+public namespace Namespace
+{
+    static int internalVar;
+
+    public static int publicVar;
+}
+
+enum InternalEnum
+{
+    A,B,C
+}
+public enum PublicEnum
+{
+    D,E,F
+}
+
+struct InternalStruct { int x; }
diff --git a/tests/diagnostics/internal-visibility/this-module.slang b/tests/diagnostics/internal-visibility/this-module.slang
new file mode 100644
index 000000000..98e0f3d08
--- /dev/null
+++ b/tests/diagnostics/internal-visibility/this-module.slang
@@ -0,0 +1,26 @@
+//DIAGNOSTIC_TEST:SIMPLE(filecheck=CHECK):
+
+module "this-module";
+
+import "that-module";
+
+void test()
+{
+    PublicStruct s;
+    // CHECK:{{.*}}(11): error 30600:
+    s.x = 1; // Error.
+    // CHECK-NOT:{{.*}}error
+    s.y = 2; // OK.
+    publicMethod(); // OK.
+    publicFunc2();  // OK.
+    Namespace.publicVar = 1; // OK.
+    Namespace.publicVar2 = 1; // OK.
+    // CHECK:{{.*}}(19): error 30600:
+    Namespace.internalVar = 1; // error.
+    // CHECK:{{.*}}(21): error 30600:
+    InternalEnum e; // Error.
+    // CHECK:{{.*}}(23): error 30600:
+    InternalStruct s1; // Error.
+    // CHECK:{{.*}}(25): error 30600:
+    internalMethod(); // Error.
+}
diff --git a/tests/diagnostics/private-visibility.slang b/tests/diagnostics/private-visibility.slang
new file mode 100644
index 000000000..7c0bad970
--- /dev/null
+++ b/tests/diagnostics/private-visibility.slang
@@ -0,0 +1,44 @@
+//DIAGNOSTIC_TEST:SIMPLE(filecheck=CHECK):
+
+struct MyType
+{
+    private int member;
+    private int func()
+    {
+        return member;
+    }
+    struct SubType
+    {
+        int member2;
+        int func2(MyType m)
+        {
+            return m.member + member2; // OK.
+        }
+    }
+    int func1() { return member; }
+
+    private __init() { member = 0; }
+    
+    private __subscript(int i)->int
+    {
+        get { return member; }
+        set { member = newValue; }
+    }
+    // CHECK:{{.*}}(28): error 30601:
+    public void publicMethod() {} // ERROR.
+}
+
+void test()
+{
+    // CHECK:{{.*}}(34): error 30600:
+    MyType t; // ERROR.
+    // CHECK-NOT:{{.*}}error
+    t.func1(); // OK.
+    // CHECK:{{.*}}(38): error 30600:
+    t.func(); // ERROR.
+    // CHECK:{{.*}}(40): error 30600:
+    t[0] = 1; // ERROR.
+
+    // CHECK:{{.*}}(43): error 30600:
+    t.member = 2;
+}
diff --git a/tests/diagnostics/visibility.slang b/tests/diagnostics/visibility.slang
new file mode 100644
index 000000000..724ec30e7
--- /dev/null
+++ b/tests/diagnostics/visibility.slang
@@ -0,0 +1,23 @@
+//DIAGNOSTIC_TEST:SIMPLE(filecheck=CHECK):
+
+// CHECK-DAG:{{.*}}(4): error 30603
+private struct MyStruct
+{}
+
+struct IS
+{
+    // CHECK-DAG:{{.*}}(10): error 30601
+    public void fp();
+}
+
+// CHECK-DAG:{{.*}}(14): error 30604
+public IS f() {}
+
+public struct PS
+{
+    // CHECK-DAG:{{.*}}(19): error 30604
+    public IS ii;
+
+    // CHECK-DAG:{{.*}}(22): error 30604
+    public property IS ii2 { get { return {}; } };
+}
diff --git a/tests/front-end/import-exported-b.slang b/tests/front-end/import-exported-b.slang
index 144f62060..e7bc49510 100644
--- a/tests/front-end/import-exported-b.slang
+++ b/tests/front-end/import-exported-b.slang
@@ -2,4 +2,4 @@
 
 // This file defines the code that will be (transitively) imported into `import-exported.slang`
 
-float foo(float x) { return x; }
\ No newline at end of file
+public float foo(float x) { return x; }
diff --git a/tests/front-end/import-subdir-search-path.slang b/tests/front-end/import-subdir-search-path.slang
index 9b7c7a520..b35802f14 100644
--- a/tests/front-end/import-subdir-search-path.slang
+++ b/tests/front-end/import-subdir-search-path.slang
@@ -7,4 +7,4 @@ __import import_subdir_a;
 // Should realize it's the same thing
 __import subdir.import_subdir_a;
 
-float bar(float x) { return foo(x); }
\ No newline at end of file
+float bar(float x) { return foo(x); }
diff --git a/tests/front-end/raw-string-literal.slang b/tests/front-end/raw-string-literal.slang
index 321f183c7..7297c27e1 100644
--- a/tests/front-end/raw-string-literal.slang
+++ b/tests/front-end/raw-string-literal.slang
@@ -17,7 +17,7 @@ void printLines(NativeString text)
     }
 }
 
-public __extern_cpp int main()
+export __extern_cpp int main()
 {
     printLines(
         R"(This is line 1.
@@ -25,4 +25,4 @@ public __extern_cpp int main()
         "Hello World"
         )");
     return 0;
-}
\ No newline at end of file
+}
diff --git a/tests/front-end/subdir/import-subdir-a.slang b/tests/front-end/subdir/import-subdir-a.slang
index 3962d4662..e973d5cbf 100644
--- a/tests/front-end/subdir/import-subdir-a.slang
+++ b/tests/front-end/subdir/import-subdir-a.slang
@@ -2,4 +2,4 @@
 
 // This is the imported code.
 
-float foo(float x) { return x; }
\ No newline at end of file
+public float foo(float x) { return x; }
diff --git a/tests/ir/string-literal-module.slang b/tests/ir/string-literal-module.slang
index 96fb62088..245b4b3a2 100644
--- a/tests/ir/string-literal-module.slang
+++ b/tests/ir/string-literal-module.slang
@@ -1,6 +1,6 @@
 //TEST_IGNORE_FILE:
 
-int doSomethingElse()
+public int doSomethingElse()
 {
     return getStringHash("Try another");
 }
diff --git a/tests/language-feature/extensions/extension-import-helper.slang b/tests/language-feature/extensions/extension-import-helper.slang
index c1a652645..11265762a 100644
--- a/tests/language-feature/extensions/extension-import-helper.slang
+++ b/tests/language-feature/extensions/extension-import-helper.slang
@@ -2,12 +2,12 @@
 
 //TEST_IGNORE_FILE:
 
-interface IThing
+public interface IThing
 {
-	float getValue();
+	public float getValue();
 }
 
-extension float : IThing
+public extension float : IThing
 {
-	float getValue() { return this; }
-}
\ No newline at end of file
+	public float getValue() { return this; }
+}
diff --git a/tests/language-feature/generics/struct-generic-value-param-import.slang b/tests/language-feature/generics/struct-generic-value-param-import.slang
index edc1b0c39..785b8146f 100644
--- a/tests/language-feature/generics/struct-generic-value-param-import.slang
+++ b/tests/language-feature/generics/struct-generic-value-param-import.slang
@@ -6,13 +6,13 @@
 // for `struct` decalrations in Slang files, including
 // any `import`ed code.
 
-interface IData {}
+public interface IData {}
 
-struct Data<let kCount : int> : IData
+public struct Data<let kCount : int> : IData
 {
-    int state;
+    public int state;
 
-    [mutating] void doStuff()
+    [mutating] public void doStuff()
     {
         state++;
     }
diff --git a/tests/language-feature/inheritance/struct-inheritance-imported.slang b/tests/language-feature/inheritance/struct-inheritance-imported.slang
index 8786b851c..16816ec97 100644
--- a/tests/language-feature/inheritance/struct-inheritance-imported.slang
+++ b/tests/language-feature/inheritance/struct-inheritance-imported.slang
@@ -1,12 +1,12 @@
 //TEST_IGNORE_FILE:
 // struct-inheritance-imported.slang
 
-struct Base
+public struct Base
 {
-    int a;
+    public int a;
 }
 
-struct Derived : Base
+public struct Derived : Base
 {}
 
-int getA(Derived d) { return d.a; }
+public int getA(Derived d) { return d.a; }
diff --git a/tests/library/library.slang b/tests/library/library.slang
index fafb1018c..3deaeab99 100644
--- a/tests/library/library.slang
+++ b/tests/library/library.slang
@@ -2,12 +2,12 @@
 
 // library.slang
 
-int doThing(int b)
+export int doThing(int b)
 {
     return b + b + 1;
 }
 
-public int foo(int a) 
+public export int foo(int a) 
 { 
     return a * a + 1 + doThing(a + 2);
 }
diff --git a/tests/reflection/multi-file-defines.h b/tests/reflection/multi-file-defines.h
index aed4c510a..0948df378 100644
--- a/tests/reflection/multi-file-defines.h
+++ b/tests/reflection/multi-file-defines.h
@@ -5,12 +5,13 @@
 #define BEGIN_CBUFFER(NAME) cbuffer NAME
 #define END_CBUFFER(NAME, REG) /**/
 #define CBUFFER_REF(NAME, FIELD) FIELD
+#define PUBLIC public
 #else
 #define R(X) /*X*/
 #define BEGIN_CBUFFER(NAME) struct SLANG_ParameterGroup_##NAME
 #define END_CBUFFER(NAME, REG) ; cbuffer NAME /*REG*/ { SLANG_ParameterGroup_##NAME NAME; }
 #define CBUFFER_REF(NAME, FIELD) NAME.FIELD
-
+#define PUBLIC
 #define sharedC     sharedC_0
 #define sharedCA    sharedCA_0
 #define sharedCB    sharedCB_0
diff --git a/tests/reflection/multi-file-shared.slang b/tests/reflection/multi-file-shared.slang
index af91d5251..91a74cd35 100644
--- a/tests/reflection/multi-file-shared.slang
+++ b/tests/reflection/multi-file-shared.slang
@@ -3,23 +3,23 @@
 
 #include "multi-file-defines.h"
 
-float4 use(float  val) { return val; };
-float4 use(float2 val) { return float4(val,0.0,0.0); };
-float4 use(float3 val) { return float4(val,0.0); };
-float4 use(float4 val) { return val; };
-float4 use(Texture2D t, SamplerState s) { return t.SampleLevel(s, 0.0, 0.0); }
+PUBLIC float4 use(float  val) { return val; };
+PUBLIC float4 use(float2 val) { return float4(val,0.0,0.0); };
+PUBLIC float4 use(float3 val) { return float4(val,0.0); };
+PUBLIC float4 use(float4 val) { return val; };
+PUBLIC float4 use(Texture2D t, SamplerState s) { return t.SampleLevel(s, 0.0, 0.0); }
 
-Texture2D sharedT R(: register(t2));
-SamplerState sharedS R(: register(s2));
+PUBLIC Texture2D sharedT R(: register(t2));
+PUBLIC SamplerState sharedS R(: register(s2));
 
-BEGIN_CBUFFER(sharedC)
+PUBLIC BEGIN_CBUFFER(sharedC)
 {
-	float3 sharedCA;
-	float  sharedCB;
-	float3 sharedCC;
-	float2 sharedCD;
+	PUBLIC float3 sharedCA;
+	PUBLIC float  sharedCB;
+	PUBLIC float3 sharedCC;
+	PUBLIC float2 sharedCD;
 }
 END_CBUFFER(sharedC, register(b2))
 
-Texture2D sharedTV R(: register(t3));
-Texture2D sharedTF R(: register(t4));
+PUBLIC Texture2D sharedTV R(: register(t3));
+PUBLIC Texture2D sharedTF R(: register(t4));
diff --git a/tests/reflection/reflect-imported-code.slang b/tests/reflection/reflect-imported-code.slang
index 20beb94b8..4600a371c 100644
--- a/tests/reflection/reflect-imported-code.slang
+++ b/tests/reflection/reflect-imported-code.slang
@@ -2,13 +2,13 @@
 
 // Imported code used by `reflect-imported-code.hlsl`
 
-float4 use(float4 val) { return val; };
-float4 use(Texture2D t, SamplerState s) { return t.Sample(s, 0.0); }
+public float4 use(float4 val) { return val; };
+public float4 use(Texture2D t, SamplerState s) { return t.Sample(s, 0.0); }
 
-Texture2D 		t_i;
-SamplerState 	s_i;
+public Texture2D t_i;
+public SamplerState 	s_i;
 
-cbuffer C_i
+public cbuffer C_i
 {
-	float c_i;
+    public float c_i;
 }
diff --git a/tests/vkray/callable-shared.slang b/tests/vkray/callable-shared.slang
index 09e76aab1..85d72a5f7 100644
--- a/tests/vkray/callable-shared.slang
+++ b/tests/vkray/callable-shared.slang
@@ -1,8 +1,8 @@
 // callable-shared.slang
 //TEST_IGNORE_FILE:
 
-struct MaterialPayload
+public struct MaterialPayload
 {
-	float4 albedo;
-	float2 uv;
+	public float4 albedo;
+	public float2 uv;
 };